[jackandjohn]

As a computer tech, I know the importance of 'being grounded' (which actually in this case means keeping everything at the same electrical potential), and I find myself curious:


Is there an upper limit to the electrical potential of a human body?


Let's say, hypothetically, that we're operating in an isolated space, standing on a hypothetical type of rubber floor that would transfer zero electricity no matter the voltage or amps, and we had a generator capable of producing any amount of electricity inside this isolated environment.

Also on the table: Is this type of question valid? Am I using terms incorrectly or misunderstanding the fundamentals?


Respect for the experts.

 

[bkmichael65]

In high voltage line work, the lineman bond themselves to the transmission lines of over 100kV. So as long as you have your hypothetical floor that is impervious to dielectric breakdown, I would guess you're good to go at whatever voltage you produce

 

[Speedskater]

If by potential you mean voltage between two reference points then there is almost no limit. A human standing on dirt acts as a small capacitor to that dirt. Maybe a 100 to 200pF cap. there will be some small DC charge between the human (one cap plate) and the dirt (the other cap plate). If you move the two cap plates apart the voltage between them increases. A basketball player may have more than 1000V difference when they jump to the basket. A parachutist maybe 100,00 Volts.

But there is just about ZERO current or power involved in this phenomenon!

 

[Big John]

I've never heard of anything bad from exposure to an electric field alone. Like micheal said: At extremely-high and ultra-high voltage, maintenance is performed by bonding onto the lines, so the guys are working in fields upwards of 765,000 volts.

 

[Mshea]

Being at a potential difference only has consequences at the moment we seek to equalize that difference. IE I can be a million volts differnt than the ground but only face any danger as I step off toward the lower potential. If I bridge on to the other is when we get the bas outcomes. In an airplace we could be several hundred thousand volts relative to earth and it is no problem fo the plane or its occupants.

 

[wildleg]

Being at a potential difference only has consequences at the moment we seek to equalize that difference. IE I can be a million volts differnt than the ground but only face any danger as I step off toward the lower potential. If I bridge on to the other is when we get the bas outcomes. In an airplace we could be several hundred thousand volts relative to earth and it is no problem fo the plane or its occupants.

I would worry about any voltage that has the approaches the dielectric ability of the environment (air) to protect you. It is unlikely that a million volts would not be hazardous in the example you provided.

Also, I suppose it goes without saying that high frequency waveforms are entirely more hazardous than the low frequencies of normal distribution and hangar power, since they can cook you in other ways.

as to the OP, the human body has characteristics that vary so widely, the question is hard to answer even for experts, which is why some have done the fairly extensive testing that they have to date in order to come up with the 5 to 7ma or so gfi specs that are so prevalent. An upper limit makes little sense in terms of providing protection to individuals, because a little excitement (sweat glands opening) would change the situation drastically in seconds for almost any individual, not to mention a cut, etc. So the scenario reduces to basic protection (gfi ranges for limiting current) at low voltages or PPE; anything in between increases somone's liability.

 

[chicken steve]

Although somewhat macabre at first sniff, the people that operate this device>

actually monitor and record bodily resistances

~CS~

 

[jackandjohn]

The point about linemen is definitely a great example for answering this question, and had me spending a few hours just watching how they work on live wires.

I'm now curious about whether they feel anything different when connected to the wires (physically or mentally), but I'm starting to think that they wouldn't once the potential is equalized.

 

[jackandjohn]

I would worry about any voltage that has the approaches the dielectric ability of the environment (air) to protect you. It is unlikely that a million volts would not be hazardous in the example you provided.

This is an interesting side-note, and I can easily see how high enough power would complete a circuit depending on the humidity of the air. Has this sort of thing happened that you know of?

Also, I suppose it goes without saying that high frequency waveforms are entirely more hazardous than the low frequencies of normal distribution and hangar power, since they can cook you in other ways.

Could you explain more about this?

as to the OP, the human body has characteristics that vary so widely, the question is hard to answer even for experts, which is why some have done the fairly extensive testing that they have to date in order to come up with the 5 to 7ma or so gfi specs that are so prevalent. An upper limit makes little sense in terms of providing protection to individuals, because a little excitement (sweat glands opening) would change the situation drastically in seconds for almost any individual, not to mention a cut, etc. So the scenario reduces to basic protection (gfi ranges for limiting current) at low voltages or PPE; anything in between increases somone's liability.

I've read this through a few times, and I must admit to not grasping it entirely - are you talking about current flow through a human? If we had a hypothetical perfectly isolated space (and hypothetically non-conductive air), I thought there would be no chance of electrical flow through a person. Or are you saying that at higher voltages, current will flow through some method regardless?

 

[jackandjohn]

... at first sniff...

:whistling2:
I see what you did there.

 

[Sparky305]

This is an interesting side-note, and I can easily see how high enough power would complete a circuit depending on the humidity of the air. Has this sort of thing happened that you know of?

I think it would look like lightning

 

[jackandjohn]

I think it would look like lightning

Hahahahahaahahahahaha!

Yes, of course you are right! I'm not sure why I didn't question my idea of electricity simply "jumping" between the clouds and the air. Quick research confirms my cognitive gap; electricity is finding the shortest path between two different charges, and in the case of bridging a gap, is actually overcoming the resistance of the air in order to use it as a path.

I'm probably stating the obvious to people on this forum, but maybe I'll help one other person who has skipped over that part somehow.

 

[seige]

This guy works on high voltage lines 500ka and up, so i don't think there is an upper limit.

Great video

 

[Speedskater]

See:
http://en.wikipedia.org/wiki/Van_de_Graaff_generator